Intravenous liquid delivery system

ABSTRACT

The intravenous feeding pump actuator of the present invention is driven by a small, very slow speed motor and a gear train, such as one rotating the output shaft at a speed of one revolution per minue (1 r.p.m.). The single motor drives a readily replaceable cam which is slipped into position on the drive shaft and needs no other means for attaching it thereto. Each of the cams normally supplied with the actuator is designed to give a predetermined number of rocking movements per minute to a cam follower which directly operates the associated intravenous pump, and simultaneously controls the limit of travel of the cam follower and thus the length of the stroke of the pump operator. It will be understood that each of the cams will provide for a different flow rate for the associated pump by controlling the number of strokes per minute and the length of each stroke and is readily changeable so that one can be quickly and easily removed and another placed in its stead when determined by operating conditions.

RELATED APPLICATIONS

This application is a continuation of application Ser. No. 627,842,filed on Nov. 3, 1975 now abandoned.

BACKGROUND OF THE INVENTION

In recent years there has been a very rapidly growing use of forciblypumping blood or various feeding solutions into the veins of a patientby means of positively operated pumping devices. Such devices are muchmore accurate in the delivery of liquid to the patient than the olderfeeding by gravity only. Often, the intravenous feeding requires thedelivery of very small amounts from 0.5 milliliters per hour up to asmuch as 500 to 1500 milliliters per hour (the equivalent of about 16 and48 ounces, respectively, per hour). At the lower rates of feed there isfrequent clogging of the delivery tube or needle which delivers thematerial into the veins of the patient and there is also considerableinaccuracy in the amount delivered over a period of time. This requiresfrequent checking of the gravity feed of such liquid to a patient by anurse, or other qualified person. The present invention relates to anactuating device for a pump whereby the number of strokes in a givenunit of time, such as one minute, and the length of the stroke (which isequivalent to saying the amount of fluid per stroke) is variable over awide range. In this respect, the present invention comprises a bigimprovement over the pump actuator shown in my prior patent, U.S. Pat.No. 3,798,892, issued Mar. 26, 1974, as it is not only much smaller andtherefore more easily portable, but is also more readily adjusted by thenurse or doctor in charge of administering the fluid to the patient. Itis obvious that such a driver, or actuator, must be positive in itsoperation and must be readily adjustable to provide a wide range ofdelivery. The device of the present invention is more practical thanthat of my former patent in that it relieves the nurse or doctor on thefloor from having to readjust the actuator each time it is used. It is agrowing development in the field of medicine, particularly in the betterhospitals, to prepare the material to be delivered in the hospitalpharmacy and deliver it properly measured and marked with properoperating instructions to the floor where the patient is located so thatthe nurse does not have to take time to do a lot of figuring oradjusting of equipment. Such devices are disclosed in my copendingapplications, Ser. No. 514,219, for Measured Volume Drug AdministrationDevice, filed Oct. 11, 1974, now U.S. Pat. No. 3,965,897, or Ser. No.538,372, entitled Drug Dispenser for Use With Intravenous Feeding Pump,filed Jan. 3, 1975, now U.S. Pat. No. 3,976,068. In such hospitals,using the present invention, the pharmacy would also send to the nurses'station the proper cam to be used for the pump actuator so that thedoctor or nurse would not be required to determine which cam should beused and what the length of stroke of the pump actuating cam followershould be.

As indicated above, the device of the present invention includes a setof cams which are easily removable from, or inserted into, the pumpactuator. Thus, an operator has merely to set the material to be fed,the necessary tubing, sterilized pump, the proper cam (all of which canbe furnished by the hospital pharmacy) into the pump actuator already atthe bedside, insert the needle into the patient and initiate operationof the pump actuator. All of this is done without the operator (who isoften very busy) having to bother about determining the number ofstrokes per minute, the length of each stroke, or otherwise setting thedevice.

OBJECTS OF THE INVENTION

It is an object of this invention, therefore, to provide a driver, oractuator, for an intravenous delivery pump which is extremely accuratein its operation and which can be more readily adjusted to provide for avery wide range of delivery volumes to a patient, than is now possible.

It is another object of this invention to provide a pump actuator whichcan be readily adjusted, even while in use, with the delay of only a fewseconds necessary to slip one operating cam off the drive shaft andreplace it by another.

These and other objects of the present invention will be apparent fromthe detailed specification which follows when taken in view of thedrawings which are a part hereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view, with the cover plate removed, of the device ofthe present invention in an operating condition and showing the pump ofU.S. Pat. No. 3,874,826.

FIG. 2 is a side view, principally in cross-section, of the device ofFIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The device of the present invention is contained within a casing 10formed of any suitable material, such as a molded plastic shell havingintegral side walls, not identified. A partition plate 11, shownparticularly in FIG. 2, is fastened in an intermediate location betweenthe back 16 and a partial front mounting plate 15. This partition 11 canbe held in proper position by any suitable means, such as studs 12. Thepartial front mounting plate 15 extends only over the upper portion ofthe casing and is fastened by suitable means to the back 16 by means notshown. The upper part of the casing is covered by a front face member 13mounted on the partial front mounting plate. A cam well 14, open at thefront, is attached to the partition by any suitable means, such asscrews 17.

A slow speed motor 20 and its integral gear box 21 are rigidly securedwithin the casing 10 by any suitable means, such as stud 22 and spacer23. The output shaft 24 from the gear box 21 faces toward the front ofthe device and is provided with some means, such as the pin 25, whichextends through the shaft 24 and is adapted to fit within a slot 31 inthe hub 32 of a spider 30. The spider 30 is held on the shaft 24 by anysuitable means, such as C-ring fastener 33. The spider is provided witha plurality (four in the preferred form as shown in the drawings) ofarms 34, each of which is provided at its outer end with a forwardlyturned ear, or bracket 35. It is thus seen that the operation of themotor 20 will drive the mounting spider 30 at some predetermined slowspeed, such as 1 r.p.m.

A cam 40, preferably circular in shape, is adapted to be inserted overthe drive spider 30. Preferably it has a centrally located truncatedconical projection which might appear to be a hub which actually is onlya handle for ease in manipulating the cam 40. The cam 40 is providedwith a suitable plurality (four in the embodiment shown) of slots 42 forreceiving the ears 35 on the spider 30. It can be noted at this pointthat the cam 40 is not locked to the drive shaft 25 or the spider 30,but is loosely mounted thereon. It is held in the proper position by theperipheral edge 47 of the cam riding on the bottom wall of the cam well14. The cam is held within the well by means of a pair of holding lugs46 formed on the lower section of the circular wall of the well 14 whichengage the face of the cam 40 adjacent the edge thereof and by the upperedge of the cam being held in proper position by lying behind the nose56 of the cam follower 55 to be described shortly. The cam 40 isprovided on its rear face with a circular peripheral spacer wall 43which engages a plurality of lugs, or bosses 44 formed on the interiorface of the well 14. Thus the cam is, in effect, centerless and is heldin its proper operating position by lying against the lugs 44 of thewell and behind the holding lugs 46 and the nose 56 of the cam followerarm 55.

The cam 40 is provided with a cam wall or projection 45 on its outerface. In the embodiment shown in FIG. 1, this cam face 45 has tendepressions 48, each of which is preceded by a gradual rise 49, thusproviding ten operations of the cam follower 55 in each revolution ofthe cam 40. The cam follower 55 is pivotally mounted on the partitionplate 11 by any suitable means, such as stud 57. The follower arm 55 isprovided with a forwardly offset nose 56 which, when the cam 40 andfollower arm 55 are in operative position, will ride on the periphery ofthe cam and will lie against the outer face, thereby holding the top ofthe cam in its proper position. When the cam follower 55 is not rockedby the cam ridge 45, the shoulder between the main portion of thefollower arm 55 and its offset nose 56 will ride upon the periphery ofthe cam 47, as shown in FIG. 2. However, when the nose 56 is rocked byengagement with a rise 49 of the camming section 45, the follower arm 55will obviously rock around its pivot 57.

In the embodiment shown, the follower arm 55 is provided with thefailure alarm system described in my co-pending application, Ser. No.488,581, filed July 15, 1974 and entitled Intravenous Pump Failure AlarmSystem, abandoned in favor of U.S. Pat. No. 4,056,333. Briefly, thiscomprises an auxiliary arm 58 pivotally mounted on the follower arm 55by any suitable means, such as stud 59. The auxiliary arm 58 carries asuitable Micro-Switch 60 mounted thereon which is engaged by a bracket61 formed on the forward projecting arm of the follower arm 55. By thisconstruction, the Micro-Switch 60 will be held in one position when thearms 58 and 55 operate together. However, when the arm 58 fails tofollow the arm 55, then the switch 60 is operative to actuate an alarmsystem by changing the setting of the switch 61. This alarm system maycomprise a signal light 80 shown at the top of FIG. 1, but obviouslycould also be an audible signal or signals at the nurses' station. Inthe preferred embodiment of the invention, both the follower arm 55 andthe auxiliary arm 58 are provided with a nose 62 on their outer endswhich lie between a pushbutton 63 and a bracket 64 that is looselycontained within the button 63, as shown in FIG. 1.

The actuator of the present invention is designed particularly to beoperative with, or upon, the pump of the kind described in my prior U.S.Pat. No. 3,874,826, in which the bracket 64 engages the outer end of aplunger 65 which is mounted for reciprocatory movement with respect to apump housing 66. The pump housing 66 is constructed in the mannerdisclosed in U.S. Pat. No. 3,874,826 and provides an inlet chamber 67and an outlet chamber 68. The housing 66 is also provided with an inlet69 opening into the inlet chamber 67 and outlet 70 which opens from theinlet chamber into the outlet chamber 68. The inlet 69 is adapted to beconnected by a tube 71 to a suitable source (not shown) of intravenousliquid. The flow of liquid through the inlet 69 is controlled by a floatvalve assembly 72. The flow of liquid through the outlet 70 from theinlet chamber 67 is controlled by another float valve assembly 73. Theoutlet chamber 68 is provided with an outlet 74 which is connected by atube 76 to the patient which is to be supplied with the intravenousliquid.

The reciprocatory plunger 65 extends into the housing 66 and has aportion thereof extending into the chamber 65 which is enclosed by aflexible rubber booth 77. The reciprocatory plunger 65 is movablebetween innermost and outermost positions with respect to the chamber67. The plunger 65 is returned to its outermost position by the flexiblerubber booth 77 and to its innermost position by the operation of therocker arm 55. The rocking of the arm 55 will depress the bracket 64 andthus push the plunger into the pumping chamber to pump liquid therefrom.At the end of the pumping stroke, the arm 55 is returned to itsinoperative position by a tension spring 65 tensioned between thefollower and the front plate 15 of the device. The plunger in this pumpis returned to its inoperative position by some resilient means, such asa rubber sheath (not shown or described herein but which is fullyexplained and described in the above-mentioned patents). Since the pumpis not part of this invention, it will not be further described but itwill be noted that the alarm system is dependent upon the failure of theresilient means for returning the pumping plunger to its inoperativeposition, which may occur from a number of reasons, such as breaking ofthe resilient means, blockage of the supply of fluid, or the like. Whatis important in this connection is that the follower arm 55 of thepresent invention can be adapted to use the alarm system of myco-pending application, Ser. No. 488,581 above mentioned, now U.S. Pat.No. 4,056,333 and this means is shown in FIG. 1. In addition to thealarm light 80 already mentioned, it is preferred that the device of thepresent invention also includes a jack 81 for transmitting a failuresignal from the bedside of a patient to a central location, such as anurses' station. Also included would be the conventional operatingswitch 82 to control power to the pump actuator.

It is believed that the operation of the present device will be obvious.Briefly stated, it includes the installation of a pump, not shown, withits operating plunger against the bracket 64 and the pump placed in asuitable location adjacent the bedside of a patient. The material to beinjected into the patient can be supplied to the nurses' station by thehospital pharmacy, together with the particular cam designed to providethe prescribed dosage rate. In the event a saline solution or blood isto be injected together with a prescribed medication, the medication canbe provided by the hospital pharmacy by using a drug injection device ofthe kind described in my copending application Ser. No. 514,219, filedOct. 11, 1974, now U.S. Pat. No. 3,965,897 or Ser. No. 538,372 filedJan. 3, 1975, now U.S. Pat. No. 3,976,068. The pump would be filled withfluid to be pumped and air driven from the system as described in saidpump patent. To secure the necessary pump operation, a cam 40 will beplaced in the cam well 14 by lifting the nose 56 of follower arm 55 awayfrom the cam, setting the cam behind the holding lugs 46 and over thespider 30, pushing the top of the cam back against the spacing lugs 44,and then setting the nose 56 over the face of the cam. The cam isthereby held in proper operating position. The number of operations perrevolution is determined by the number of rises 49 on the cam wall 45and the length of the stroke will be determined by the depth of thedepression 48 following each such rise. It is obvious that by varyingthe number of rises and depressions on a cam and the depth of eachdepression, the amount to be pumped can be controlled over wide limits.The pump can be designed for an unlimited number of different flow ratesranging between 0.5 milliliters per hour to 1,000 milliliters per hour.It will be understood that each separate rate of flow will require aseparate cam specifically designed for that volume of operation.

When viewed as a method of providing a "fail-safe" system of intravenousfeeding of a patient, it includes the steps of:

(1) the hospital pharmacy provides the nurses' station with the materialto be injected into the medication (and if medication is to be added toanother feeding solution, that could be provided by using apower-operated drug injection device such as one of those described inthe applications referred to in the preceding paragraph) and thespecific cam designed to feed the solution at the prescribed rate;

(2) at the proper time the nurse or aide merely attaches the material tobe injected to the pump and changes the cam in the pump actuator.

By this method a nurse's aide can be used to treat the patient, as nomeasurement of medication is required at that time as all material to beinjected was provided by the pharmacy, and no adjustment of the pumpactuator is necessary as that has also been provided by the pharmacy. Itis thus obvious that much of the work that now has to be done by a nursecan be done by lesser qualified personnel as on measurements oradjustments are necessary at the patient's bedside. It also providesmeans whereby the time required to prepare for the intravenous feedingof a patient is materially reduced, as bedside or nurses' stationmeasurements or adjustments need no longer be made. This saving of timeby floor personnel is important in many hospitals that find itimpossible to find suitably trained personnel to adequately handle thepatient load.

It is believed obvious that many modifications can be made in thepresent invention. For example, the cam plates could be rigidly securedon the drive shaft 24 by means of a locking nut or otherwise, althoughthat would require the nurse or doctor operating the pump to lay downthe cam to be used, to manually release the cam that had been in themachine, to then replace it and lock the new one on the shaft. It isbelieved the present embodiment makes it easier and quicker for theattendant to set the proper cam within the machine. It is also obviousthat other volumes could be provided for by changing the number of cams,cam rises and depressions on the face of the cam so that volumes couldbe more or less than those specified. It is also believed obvious thatwhile a continuous cam ridge 45 is preferred, that a plurality ofdisjointed rises could be used as well. It is also obvious that thespeed above mentioned can be varied from that described and the samequantities can be pumped per hour by changing the number of lobes on thevarious cams and the length of each stroke by varying the distancebetween the top of the rise and the depth of the depression to which thecam follower 55 can fall.

What is claimed is:
 1. In an intravenous liquid delivery system fordelivery of intravenous liquid from a source of supply to the patient,intravenous pump having a liquid filled chamber and having an inletadapted to be connected to the source of supply, and an outlet adaptedto be connected to the patient, a reciprocating plunger for causing theflow of intravenous liquid to be pumped through the pump chamber fromthe inlet to the outlet and an actuator for causing the reciprocatorymovement of said plunger, said actuator including housing, drive meanscarried by the housing and having a rotatable output shaft, a set ofremovable cam members, each of said cam members having a plurality ofpeaks and valleys, said peaks and valleys on each of said cam membersbeing different from the other cam members, a selected one of said cammembers being coupled to said shaft so that it is driven thereby, a camfollower carried by said housing, yieldable means urging the camfollower into engagement with said cam member so that the cam followeris caused to move in accordance with the peaks and valleys of theselected cam as the rotatable shaft is rotated and means coupled to thecam follower for providing reciprocatory motion from the cam followerfor driving the plunger of said pump whereby intravenous liquid isdispensed by the pump in accordance with the selected one of said cammembers.
 2. In an intravenous liquid delivery system, an intravenouspump having a liquid filled chamber and having an inlet adapted to beconnected to the source of supply and an outlet adapted to be connectedto the patient, valve means for controlling the flow liquid through theinlet and the outlet of the pump, a reciprocatory plunger for causingthe flow of intravenous liquid to the pump chamber from the inlet to theoutlet and an actuator for causing the reciprocatory movement of saidplunger, said actuator comprising a casing, drive means carried by thecasing and having a rotatable output shaft, cam holder means carried bysaid output shaft, a set of removable cam members adapted to beremovably mounted on said cam holder, means for removably retaining aselected one of cam members on said cam holder, a cam follower pivotallymounted in the said casing, each of said cam members having portionsdiffering from the cam portions of the others of the cam members, saidportions being adapted to be engaged by said cam follower causingmovement of the cam follower, and means coupled to said cam follower forproviding reciprocatory motion for causing reciprocatory movement ofsaid plunger whereby the intravenous liquid is dispensed by the pump ata rate at least in part determined by the selected one of said cammembers.
 3. A system as in claim 2 wherein the means for removablyretaining said cam member comprises spacing lugs mounted on the casingadapted to hold the cam in an operating position and the cam follower isprovided with an offset nose adapted to seat against the face of the camin opposition to the center of said lugs.
 4. A system as in claim 2wherein said cam comprises a flat disc, a cam wall in one face of saidcam adapted to be engaged by said follower.
 5. A system as in claim 2wherein the means for holding said cam on said output shaft comprisesthe hub member mounted on said shaft, a plurality of radial arms on saidhub, said cam being provided with apertures, and projections carried bythe outer ends of said arms adapted to engage the apertures in said cam.